Yamaha MBK MW125 2014, Service Manual

Page: 340 / 380

FUEL INJECTION SYSTEM
8-43
TIP
• If fault code numbers “37” and “46” are both indicated, take the actions specified for fault code number
“46” first.
• If fault code numbers “37” and “42” are both indicated, take the actions specified for fault code number
“42” first.
• If fault code numbers “37” and “79” are both indicated, take the actions specified for fault code number
“79” first.
• If fault code numbers “37” and “61” are both indicated, take the actions specified for fault code number
“61” first.
B-2 Connection of wire harness
ECU coupler.
Check the locking condition of
the coupler.
Disconnect the coupler and
check the pins (bent or broken
terminals and locking condition
of the pins). Improperly connected
→
Con-
nect the coupler securely or re-
place the wire harness.
Execute the diagnostic mode.
(Code No. 54)
ISC valve operation sound is
heard.
→
Go to item B-8.
ISC valve operation sound is
not heard.
→
Go to item B-3.
B-3 Wire harness continuity. Open or short circuit
→
Replace
the wire harness.
Between ISC coupler and ECU
coupler.
Pink–Pink
Gray–Gray
Green/yellow–Green/yellow
Sky blue–Sky blue
Execute the diagnostic mode.
(Code No. 54)
ISC valve operation sound is
heard.
→
Go to item B-8.
ISC valve operation sound is
not heard.
→
Go to item B-4.
B-4 Installed condition of ISC valve. Check the mounting area for
looseness or pinching.
Make sure that the installation
position is correct.
Check the intake air passages
for air leaks. Execute the diagnostic mode.
(Code No. 54)
ISC valve operation sound is
heard.
→
Go to item B-8.
ISC valve operation sound is
not heard. Go to item B-5.
B-5 Power voltage is too low. Check battery voltage.
Refer to “CHECKING AND
CHARGING THE BATTERY” on
page 8-60. Execute the diagnostic mode.
(Code No. 54)
ISC valve operation sound is
heard.
→
Go to item B-8.
ISC valve operation sound is
not heard.
→
Go to item B-6.
B-6 Faulty ISC valve operation. Replace the ISC valve.
Refer to “CLEANING THE ISC
(IDLE SPEED CONTROL)
UNIT AND THROTTLE BODY”
on page 7-9. Execute the diagnostic mode.
(Code No. 54)
ISC valve operation sound is
heard.
→
Go to item B-8.
ISC valve operation sound is
not heard.
→
Go to item B-7.
B-7 Malfunction in ECU. Replace the ECU.
Refer to “REPLACING THE
ECU (engine control unit)” on
page 8-59. Execute the diagnostic mode.
(Diagnostic code No. 54)
Return the ISC valve to the ini-
tial opening position.
B-8 Delete the fault codes.
Start the engine and let it idle
for approximately 10 seconds.
After completing the above op-
eration, check the fault code
display.
Fault code No. 37
Item Engine speed is high when the engine is idling.